Centrifugal apparatus



Sept. 29, 1964 w. M. DIETZEL ETAL CENTRIFUGAL APPARATUS Filed June 21, 1960 A INVENTOR'SQ. Way/er Die/2e? BY Hezhwz'c MY/ermzd United States Patent 3,151,072 CENTRIFUGAL APPARATUS Walter Max Dietzei, Busseldorf-Gerresheim, and Heinrich Emil Hiiiebrand, Dusseldorf, Germany, assignors to Braunschweigische hiascliinenhauanstait A.G., Brannschweig, Germany, a corporation of Germany Filed June 21, 196i), Ser. No. 37,532 4 Claims. (Cl. 210-380) This invention relates to a continuous centrifuge, and more particularly to the type of centrifugal apparatus whereby a perforate basket is lined with an auxiliary screen. By continuous centrifuge, centrifuges are meant which are used, while running at full speed, for the continuous separation of the components of a mixture, for instance, for the continuous discharge of solid components and a liquid phase.

Auxiliary screens, as used in the case of our present invention, are relatively thin and are ordinarily employed to offer a relatively large screening surface. Up to now, difliculties were encountered in securing screens to centrifuge baskets in a manner which ensured the absence of wrinkles and creases, but a smooth screening surface free from wrinkles and creases is most important since unevenness of the screening medium increases the resistance to the motion of the material being centrifuged, and increased friction reduces the eifectiveness of centrifuges and causes screens to wear more rapidly.

Thus, the primary object of our invention is to provide a centrifuge having a screen-lined basket, with no wrinkles and creases in the screen.

Numerous attempts have already been made to fix screens to centrifuge baskets in a wrinklefree fashion, but so far such attempts have not been successful. For instance, it has been suggested to retain filter and screening media by cone-shaped inserts, expanding rings, rings made from rubber, etc. However, the use of such inserts and rings has not avoided the formation of wrinkles and folds, and in addition, the inserts and rings constitute projecting ribs which disturb the continuous movement of the material being separated and thus further incrustation. These disadvantages make themselves especially strongly felt in the case of multi-stepped centrifuges and in the case of centrifuges provided with a nonperforated bowl at the bottom.

Accordingly, other objects of the present invention center about a centrifuge having a screening medium which is free not only from wrinkles and/ or folds in the screen but also from ribs of the referred to kind, and which will ensure even movement and discharge of material.

Still other objects of the invention will become apparent from the following detailed description.

To the accomplishment of the above listed objects and the objects which will appear hereinafter, our invention consists in the apparatus elements and their relation one to the other, as are described in the specification and sought to be defined in the claims.

The specification is accompanied by a drawing in which:

FIG. 1 is a section taken in elevation through a centrifuge embodying features of the invention;

FIG. 2 is a fragmentary sectioned elevation of a modified centrifuge basket, drawn to enlarged scale;

FIG. 3 is an elevational view of another modification of a centrifuge basket;

FIG. 4 shows a detail, to enlarged scale, of the basket of FIG. 1; and

FIGS. 5, 6 and 7 show details of three or more modifications of a centrifuge basket.

Referring to the drawing in greater detail now, and initially to FIG. 1, a shaft 10 is vertically supported for rotation in a bearing assembly designated 12. The shaft has a drive pulley 14 at the lower end thereof. A basket generally designated 16 comprises a side wall 18 and a stepped bottom wall. The former consists of a perforated portion 20 and a nonperforated portion 22, and the latter consists of a central portion 24 and an annular peripheral portion 26, whereby the portion 26 is axially displaced in a downward direction relative to the central portion 24. Thus, the bearing assembly 12 as well as the shaft 10 appear enclosed in a recess formed in the bottom wall of the basket. The features so far described form no part of the present invention.

The perforate side wall portion 20 is of upwardly flaring substantially conical shape and is lined with a screening medium 28 of a mesh size such as to permit passage of the liquid component of a mixture to be separated in the centrifugal apparatus, while retaining the solid component thereon. The liquid passing through the screening medium 28 and the perforations 30 in the side wall portion 20 enters a collecting chamber 32 defined by the side wall 18 and an intermediate housing wall 34 which coaxially surrounds the side wall. The liquid collected in the chamber 32 is withdrawn therefrom through a tube 36 communicating with the chamber 32 near the bottom thereof.

The side Wall portion 22 is of downwardly flaring or opposite cone shape. In the area of transition from the side wall portion 20 to the side wall portion 22, the basket side wall is interiorly provided with an annular groove 38 (best seen in FIG. 4) defined by surfaces 40 and 42, the former reentering the basket side wall substantially vertically, and the latter reentering the basket side wall substantially horizontally. A bent portion 29 of the screening medium 28 is shown to lie against the groove formed by the surfaces 4 and 42 and to project, when viewed in a downward direction, somewhat beyond the shoulder 44 thus formed.

In FIG. 1, the numeral 46 is to designate individual members to hold the screening medium in place. The holding members are provided with a head portion 48 shaped to correspond to the groove 38, and a leg portion 50 which is screwed onto the bottom wall portion 26 as at 52.

The screen 28 is preferably preformed before its introduction into the basket. Also, it is preferre to introduce the screen into the basket and the groove 38 with a certain pretension.

With a basket and a screening medium according to the invention, the screening medium is easily put in place without the formation of wrinkles, and with the screenholding means of the invention, the bottom portion of the screen is pressed into the groove 38 and against the surfaces dtl and 42, thus ensuring perfect seating not only of the lower portion of the screen but of the entire areal extent of the screen.

Instead of individual holding members 46, a single ring-shaped holding member may be used as well. And instead of an annular groove 33, as intended to: be shown in FIGS. 1 and 4, a series of individual depressions may be provided, in which case individual holding members are preferably used.

From FIG. 1 it will further be seen that the formation 48 of the holding members 46 has the shape of a half arrow or barblike head and sandwiches the bent screen portion 29 between itself and the groove 38. With the holding members being secured to the centrifuge basket at 52, the half arrow head formations of the holding members safely hold the screen in place;

In FIG. 2, a centrifuge basket is shown the side wall 54 of which is provided with two spaced reversely shaped grooves 56 and 56'. For instance, groove 5'6 is defined by an obliquely reentrant surface 58 and a substantially horizontally extending surface 60. With the provision of the two grooves 56 and 56, the screen 62 is put in r3 (9 place with portions entering both grooves and lying against the surfaces defining both of the grooves. Two annular holding rings 64 and 64 are used to safely hold the screen in place. The use of two spaced grooves is resorted to in cases of high-walled centrifuge baskets, but a provision must be made that an upwardly directed axial stretching of the screen will not result in a beadlike formation that may block the flow of material.

Where two grooves are desired, two spaced series of individual depressions may be provided instead.

Having reference to FIG. 3, a cone-shaped centrifuge basket 66 has a side wall 63 which is shown to be perforated throughout and to be provided with individual depressions 79, each depression being preferably defined by intersecting plane surfaces.

In FIG. 5, a cylindrical centrifuge basket '72 is shown, having a depression or an annular groove '74. defined by a substantially horizontal surface '76 and a slanting surface 78.

The centrifuge basket 30 illustrated in FIG. 6 is again of conical shap. A depression or an annular groove 82 is defined by two surfaces 84 and 86, slanting in the same direction.

The centrifuge basket 83 shown in FIG. 7 is cylindri'cally shaped. A groove or depression 9i is defined by surfaces 92 and 94.

It is believed that the apparatus of our invention and the many advantages th reof will be-fully understood from the foregoing detailed description. Some of the features and advantages are reviewed hereinafter.

An apparatus as shown in FIG. 1 is used, for instance, in sugar refineries to remove the syrup from the crystallized sugar after concentaition in evaporators.

For this purpose as well as for other purposes, it is most desirable to provide the centrifuge basket with an auxiliary screen in both a wrinklefree and ribfree manner. Our present invention fully satisfies these requirements. The invention is applicable to cylindrical, conical and other basket shapes, to baskets with or without imperforate bottom bowls. The depressions provided according to the invention in the centrifuge baskets are preferably formed by intersecting plane surfaces. It is further preferred that the planes intersect at substantially right or acute angles, not at obtuse angles. While we ordinarily employ means to hold the screening medium in place, such holding means may be dispensed with when the intersecting surfaces help afford a safe enough holding support. in a construction like the one illustrated in FIGS. and 6, the screen will be held in place without the use of holding means, provided the bent parts of the screen are received in the depressed parts of the basket side wall under tension.

It will be apparent that while we have shown and described our invention in a few forms only, many changes and modifications may be made without departing from the spirit of the invention defined in the following claims.

We claim:

1. In a centrifugal apparatus for continuous separation of the components of a mixture, a centrifuge basket, a screening medium, and holding means, said basket having a side wall including a perforate and an imperforate portion and being interiorly provided in the area of transition between said portions with a first circularly extending depression, said first depression being formed by a first pair of annular surfaces reentering said side wall on the inside thereof and intersecting each other, said perforate wall portion being of upwardly widening conical shape, said screening medium being of mating cone shape and lining, and being in actual contact with, the inside of said perforate wall portion, said screening medium having a first and second edge portion, said first edge portion being in said area of transition and being pro- ,vided with a part having a second and a third pairof intersecting annular surfaces, said surfaces of said third pair forming a second circularly extending depression,

said part being shaped to be, and being, fittingly received in said first depression, said surfaces of said second pair abutting against said surfaces of said first pair, said holding means including a plurality of members, each member having a head and a terminal portion, said terminal portion being detachably secured to said basket at a place outside of said perforate wall portion, said head having a fourth pair of intersecting annular surfaces and being received in saidsecond depression to press said part against one of said reentering surfaces of said first pair and to secure said screening medium against movements toward the widening end of said perforate wall portion, said second edge portion being at said widening basket end and being unfastened, allowing said screening medium to stretch in the direction toward the widening basket end, and allowing permanent tight and wrinklefree lying of said screening medium against said perforate wall portion.

2. In the apparatus according to claim 1, one of said surfaces of each of said first, second, and third pairs extending substantially horizontally and being on the side of said imperforate wall portion, said head pressing said part against the substantially horizontal surface of said first pair. 1

3. In a centrifugal apparatus for continuous separation of the components of a mixture, a centrifuge basket, and a screening medium, said basket having a side wall including a perforate and an imperforate portion and being interiorly provided in the area of transition between said portions with a circularly extending depression, said depression being formed by a first pair of annular surfaces reentering said side Wall on the inside thereof and intersecting each other, said perforate wall portion being of upwardly widening conical shape, said screening medium being of mating cone shape and lining, and being in actual contact with, the inside of said perforate wall portion, said screening medium having a first and second edge portion, said first edge portion being in said area of transition and being provided with a part having a second pair of intersecting annular surfaces, said part being formed to be normally under tension and being shaped to be, and being, fittingly received in said depression, said surfaces of said second pair abutting against the surfaces of said first pair, said tension urging said part against one of said reentering surfaces of said first pair and securing said screening medium against movements toward the widening end of said basket, said second edge portion being at said widening basket end and being unfastened, allowing said screening medium to stretch in the direction toward the widening basket end,

and allowing permanent tight and wrinklefree lying of said screening medium against said perforate wall portion.

4. In the apparatus according to claim 3, one of the surfaces of each of said first and second pairs extending substantially horizontally and being on the side of said References Cited in the file of this patent UNITED STATES PATENTS 720,144 Hixson Feb. 10, 1903 1,216,495 Reese Feb. 20, 1917 1,292,758 Gonzalez Jan. 28, 1919 1,464,370 Novick Aug. 7, 1923 81,039 Roberts Apr. 13, 1926 16,456 Yurkovitch July 4, 1933 1,974,798 Dunning Sept. 25, 1934 2,147,792 Knight Feb. 21, 1939 5,817 Olson et al Jan. 31, 1950 2,695,133 Drury NOV. 23, 1954 8 ,054 Sanchez Apr. 21, 1959 2, 91,887 Wirth et al July 11, 1961 0 Steinaacker "Dec. 12, 1961 6,303 Durgeloh Feb. 5, 1963 9,069 Thylefors Feb. 26, 1963 

1. IN A CENTRIFUGAL APPARATUS FOR CONTINUOUS SEPARATION OF THE COMPONENTS OF A MIXTURE, A CENTRIFUL BASKET, A SCREENING MEDIUM, AND HOLDING MEANS, SAID BASKET HAVING A SIDE WALL INCLUDING A PERFORATE AND AN IMPERFORATE PORTION AND BEING INTERIORLY PROVIDED IN THE AREA OF TRANSITION BETWEEN SAID PORTIONS WITH A FIRST CIRCULARLY EXTENDING DEPRESSION, SAID FIRST DEPRESSION BEING FORMED BY A FIRST PAIR OF ANNULAR SURFACES REENTERING SAID SIDE WALL ON THE INSIDE THEREOF AND INTERSECTING EACH OTHER, SAID PERFORATE WALL PORTION BEING OF UPWARDLY WIDENING CONICAL SHAPE, SAID SCREENING MEDIUM BEING OF MATING CONE SHAPE AND LINING, AND BEING IN ACTUAL COMBAT WITH, THE INSIDE OF SAID PERFORATE WALL PORTION, SAID SCREENING MEDIUM HAVING A FIRST AND SECOND EDGE PORTION, SAID FIRST EDGE PORTION BEING IN SAID AREA OF TRANSITION AND BEING PROVIDED WITH A PART HAVING A SECOND AND A THIRD PAIR OF INTERSECTING ANNUALR SURFACES, SAID SURFACES OF SAID THIRD PAIR FORMING A SECOND CIRCULARLY EXTENDING DEPRESSION, SAID PART BENG SHAPED TO BE, AND BEING, FITTINGLY RECEIVED IN SAID FIRST DEPRESSION, SAID SURFACES OF SAID SECOND PAIR ABUTTING AGAINST SAID SURFACES OF SAID FIRST PAIR, SAID HOLDING MEANS INCLUDING A PLURALITY OF MEMBERS, EACH 